Embodiments of the present invention generally relate to a system and method of deicing water within a receptacle, such as a pond, birdbath, or the like. More particularly, embodiments of the present invention relate to systems and methods for smart deicers.
Heating or deicing systems have commonly been used to maintain unfrozen areas in fluids such as water. For example, deicing systems may be used in water tanks for livestock, fish ponds, and the like. Early deicers burned wood, coal, or gas while most deicers today are electric. A typical deicing system includes a heater coil. The heat from the coil is transferred to the fluid to keep the fluid from freezing. Electric deicers typically range from 1000 to 1500 watts and may include thermostats that are commonly used to turn the unit on or off in order to introduce heat into the fluid when freezing conditions exist.
Many property owners have ponds located within their property. During winter months in colder climates, the ponds tend to freeze over with ice. When the ponds freeze over, toxic gases are trapped under the ice and pose a hazard to fish living within the pond. If the frozen surface is not broken in order to allow toxic gases to escape, the water below the frozen surface may become overly concentrated with nitrates, for example. Thus, the ice typically is broken in order to allow the toxic gases to escape.
In order to gain access to water below the surface for various activities and provide a path for toxic gases to escape, the frozen surface of the water is typically broken, drilled, or the like, in order to provide an accessible path to the water below. However, conventional methods of providing access to the water are typically labor-intensive, time-consuming, and typically do not prevent subsequent freezing.
As an alternative to conventional methods, pond heaters may maintain an ice-free area within a body of water. However, typical pond heaters are expensive to operate because they operate between approximately 1000 and 1500 watts or more, and, as such, may be dangerous.
Deicers typically are one of three types: (1) floating deicers, wherein the heating element is suspended from a floatation device such that it operates near the surface of the fluid; (2) sinking deicers, wherein the deicer rests upon the bottom of the pond or tank, usually attached to a guard such that the heating element is not in direct contact with the bottom; or (3) drain plug deicers mounted through the drain hole in a livestock tank.
Each of these three types has its own advantages and disadvantages. A floating deicer can more accurately measure the temperature at the surface where freezing will occur, thus it can be set more accurately to turn on at the optimum temperature. However, a deicer on the surface is also within reach of animals that may interfere with its operations or attempt to flip it out of the tank.
Sinking deicers, on the other hand, are often out of sight. However, because the deicer is positioned near the bottom of the fluid and freezing occurs at the top, a temperature gradient between the top and bottom of the fluid may exist. As such, the deicer may turn on at a higher temperature and heat more of the fluid, thereby having a reduced efficiency when compared to a floating deicer.
Drain plug deicers conveniently mount through the drain hole of a livestock tank where they are out of reach of animals and the cord can be protected. However, they also share the disadvantages of a sinking deicer, and have the additional disadvantage of requiring the tank to be drained in order to install the unit.
Different consumers will have their own preference for the type of deicer to use. However, it is not always known which type will work best for a particular application until one or more of the types have been tried. Therefore, a deicer that can be converted from a floater to a sinker would combine both types into one device and give greater flexibility to the user.
Deicers typically contain a thermostat to activate the heating element whenever the fluid temperature falls to a point where freezing may occur. The following discussion assumes the fluid is water, with a freezing point of 32 degrees Fahrenheit (F). In deicers with thermostats, the thermostat will normally turn on at around 40 degrees F. and will turn off after the water temperature has risen a number of degrees. While the water will not freeze until it reaches 32 degrees F., the set point for turning on the thermostat is usually situated around 40 degrees F. to accommodate the uncertainty in accurately determining the set point during production. That is, the set points of a batch of thermostats designed to turn on at 40 degrees F. may actually have a spread of +/−7 degrees F. around that temperature.
Thermostatically-controlled deicers include a thermostat that is placed in series with the heating element. The deicers are normally preset to turn on when the fluid temperature reaches a value approaching the freezing point and turn off when the fluid temperature reaches a value tens of degrees above the freezing point. The thermostat may include bimetal arms that serve as the electrical switch for the deicer. Thus, no additional components are required. The thermostat also serves as a safety device when a thermal path is provided from the heating element to the thermostat such that it will shut off if excess heat is detected. Excess heating may occur if the heater is removed from the fluid, for example.
The thermostats used in deicers are typically of the bimetal type. Typical turn-on/turn-off set points are around 45 degrees F. and 70 degrees F., respectively. However, the actual on/off temperatures of the thermostats are usually specified with a range of 5-8 degrees F. above and below these set points. While this range is necessary in order to keep the price of the thermostats down, it is not desirable from an operation standpoint since the deicer could turn on when the water temperature is only 50 degrees F. with no danger of freezing. For a 1500 watt deicer, the operation can therefore be needlessly expensive.
Because of the higher turn-on temperature, a deicer may operate to heat the water even on days when freezing conditions do not exist. For example, the temperature of the water in a livestock tank is directly affected by the surrounding air temperature. Thus, if the air temperature drops to 20 degrees F., the water will cool until it starts freezing at 32 degrees F. Since the water temperature has dropped below its 40 degree F. set point, a deicer placed in the tank will turn on and heat the water to keep it from freezing. Suppose now, however, that the air temperature is 35 degrees F.—three degrees above freezing. The water will tend to cool down to that temperature but, once its temperature drops below 40 degrees F., the deicer will turn on to heat the water even though the water was never in danger of freezing. In that situation, energy will be wasted in heating the water.
To prevent a deicer from turning on when the air temperature is above freezing, a common practice has been to plug the deicer into a thermally-controlled outlet that senses air temperature and passes power through the outlet only when the air temperature is below a certain point. While this procedure often works to increase the efficiency of the deicer by preventing it from turning on when the air temperature is high, the present thermally-controlled outlets suffer from numerous problems. One problem is that deicers typically draw 10 Amps or more of current. As a connector is used, the contacts tend to get worn thereby increasing the resistance at the contact point. With the thermostat located in close proximity to the contacts, the heat from the connections can influence the on/off operation of the thermostat with the result that the thermostatically-controlled outlet shuts off when it should actually be turned on.
Another problem is that the thermostat employed in the temperature-controlled outlet may exhibit hysteresis that negates its benefits. For example, consider a thermostat that turns on when the temperature drops to 35 degrees F. and turns off when the temperature rises to 45 degrees F., thus exhibiting a ten degree hysteresis. If the air temperature drops to 25 degrees F. the thermally-controlled outlet will be activated and a deicer plugged into it will be allowed to operate to keep the livestock tank from freezing. Suppose now, however, that the air temperature climbs to 39 degrees F. The tank is no longer in danger of freezing, but the deicer will still be allowed to turn on. Thus, energy is expended because the deicer is set to turn on at 40 degrees F. and the thermally-controlled outlet is still activated because the air temperature has not climbed above 45 degrees F.
Thus, it is highly desirable to have a deicer that is capable of making more intelligent decisions regarding temperature conditions. Therefore, there exists a need for a smart deicer.